Organize intrinsics const evaluability checks #61835
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -529,51 +529,12 @@ impl Qualif for IsNotPromotable { | ||
| let fn_ty = callee.ty(cx.body, cx.tcx); | ||
| match fn_ty.kind { | ||
| ty::FnDef(def_id, _) => { | ||
| let is_const_fn = | ||
| cx.tcx.is_const_fn(def_id) || | ||
| cx.tcx.is_unstable_const_fn(def_id).is_some() || | ||
| cx.is_const_panic_fn(def_id); | ||
|
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There was a problem hiding this comment. Isn't this There was a problem hiding this comment. Ah dang I might have mixed this up again with There was a problem hiding this comment. Note that this can't go wrong anymore, without triggering a mismatch with @ecstatic-morse and I will be removing the copy from There was a problem hiding this comment. I just hope we get the intrinsic thing landed as part of this refactor, it's been 4 months or so.^^ There was a problem hiding this comment. Oh yeah this PR can land at any time, and I think There was a problem hiding this comment. Okay, but what about the new const checking pass? Does that still allow calling intrinsics? There was a problem hiding this comment. That's a good question for @ecstatic-morse. There was a problem hiding this comment. I reserved a spot for these checks here. I think we just need to call the There was a problem hiding this comment. I missed that this was baked into |
||
| if !is_const_fn { | ||
| return true; | ||
| } | ||
| } | ||
| _ => return true, | ||
| @@ -943,6 +904,68 @@ impl<'a, 'tcx> Checker<'a, 'tcx> { | ||
| } | ||
| } | ||
|
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| /// Check fn in const context with supplied feature gates | ||
| fn check_fn_in_const_ctx(&mut self, def_id: DefId) -> () { | ||
| // Only in non-const functions it is perfectly fine to call any | ||
| // function, even ones whose constness is unstable. Everywhere else | ||
| // we need to check the appropriate feature gates. | ||
| if self.mode.requires_const_checking() { | ||
| let unleash_miri = self | ||
| .tcx | ||
| .sess | ||
| .opts | ||
| .debugging_opts | ||
| .unleash_the_miri_inside_of_you; | ||
| if self.tcx.is_const_fn(def_id) || unleash_miri { | ||
| // stable const fns or unstable const fns | ||
| // with their feature gate active | ||
| // FIXME(eddyb) move stability checks from `is_const_fn` here. | ||
| } else if self.is_const_panic_fn(def_id) { | ||
| // Check the const_panic feature gate. | ||
| // FIXME: cannot allow this inside `allow_internal_unstable` | ||
| // because that would make `panic!` insta stable in constants, | ||
| // since the macro is marked with the attribute. | ||
| if !self.tcx.features().const_panic { | ||
| // Don't allow panics in constants without the feature gate. | ||
| emit_feature_err( | ||
| &self.tcx.sess.parse_sess, | ||
| sym::const_panic, | ||
| self.span, | ||
| GateIssue::Language, | ||
| &format!("panicking in {}s is unstable", self.mode), | ||
| ); | ||
| } | ||
| } else if let Some(feature) | ||
| = self.tcx.is_unstable_const_fn(def_id) { | ||
| // Check `#[unstable]` const fns or `#[rustc_const_unstable]` | ||
| // functions without the feature gate active in this crate in | ||
| // order to report a better error message than the one below. | ||
| if !self.span.allows_unstable(feature) { | ||
| let mut err = self.tcx.sess.struct_span_err(self.span, | ||
| &format!("`{}` is not yet stable as a const fn", | ||
| self.tcx.def_path_str(def_id))); | ||
| if nightly_options::is_nightly_build() { | ||
| help!(&mut err, | ||
| "add `#![feature({})]` to the \ | ||
| crate attributes to enable", | ||
| feature); | ||
| } | ||
| err.emit(); | ||
| } | ||
| } else { | ||
| let mut err = struct_span_err!( | ||
| self.tcx.sess, | ||
| self.span, | ||
| E0015, | ||
| "calls in {}s are limited to constant functions, \ | ||
| tuple structs and tuple variants", | ||
| self.mode, | ||
| ); | ||
| err.emit(); | ||
| } | ||
| } | ||
| } | ||
|
|
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| /// Check a whole const, static initializer or const fn. | ||
| fn check_const(&mut self) -> (u8, &'tcx BitSet<Local>) { | ||
| use crate::transform::check_consts as new_checker; | ||
| @@ -1397,101 +1420,20 @@ impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> { | ||
| ty::FnDef(def_id, _) => { | ||
| callee_def_id = Some(def_id); | ||
| match self.tcx.fn_sig(def_id).abi() { | ||
| Abi::PlatformIntrinsic => { | ||
| match &self.tcx.item_name(def_id).as_str()[..] { | ||
| name if name.starts_with("simd_shuffle") => { | ||
| is_shuffle = true; | ||
| } | ||
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|
||
| _ => { | ||
| // check for other platform intrinsics which | ||
| // may not be usable with their unstable feature gates | ||
| // in const fn. | ||
| self.check_fn_in_const_ctx(def_id) | ||
| } | ||
| } | ||
| } | ||
| _ => self.check_fn_in_const_ctx(def_id) | ||
| } | ||
| } | ||
| ty::FnPtr(_) => { | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,5 @@ | ||
| #![feature(core_intrinsics)] | ||
| fn main() { | ||
| let x: &'static usize = | ||
| &std::intrinsics::size_of::<i32>(); //~ ERROR temporary value dropped while borrowed | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,13 @@ | ||
| error[E0716]: temporary value dropped while borrowed | ||
| --> $DIR/const-eval-intrinsic-promotion.rs:4:10 | ||
| | | ||
| LL | let x: &'static usize = | ||
| | -------------- type annotation requires that borrow lasts for `'static` | ||
| LL | &std::intrinsics::size_of::<i32>(); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use | ||
| LL | } | ||
| | - temporary value is freed at the end of this statement | ||
|
|
||
| error: aborting due to previous error | ||
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| For more information about this error, try `rustc --explain E0716`. |
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